The dog factor in brown dog tick Rhipicephalus sanguineus (Acari: Ixodidae) infestations in and near human dwellings.

Three cases of the tick Rhipicephalus sanguineus infiltration in or near human dwellings caused by dogs, and their influence on epidemiological features of human habitats have been investigated. (a) The observation of dogs kept indoors proved that single tick females could engorge and oviposit inside apartments followed by the development of subadults. (b) Abundant micropopulations of ticks were formed in small yards or gardens near the dwellings where dogs lived in kennels. (c) A huge field population of R. sanguineus was observed on a farm where watchdogs constantly patrolled along the farm perimeter. Tick abundance near the kennels and in the permanent resting sites of the dogs reached more than 30 adults per 10 min of collecting, while the number of adults on a dog reached 100. Unfed adult females under conditions of constant dog availability had a larger scutal index than females collected in the control field site. On the basis of circumstantial evidence it is possible to conclude that under the above conditions tick development may change from the normal 3-host cycle to a 2-host cycle. Ticks in the field had one complete generation per year. Ticks on the farm, as well as ticks in kennels, developed faster and a significant part of their population had two complete generations per year. R. sanguineus is the main vector and reservoir of a pathogen from the Rickettsia conorii complex, the causative agent of Israeli tick typhus. The described conglomerations of R. sanguineus create a great risk to humans who can be attacked by infected ticks in and around their homes, even in large towns. Such a feature of the tick life history most likely exists not only in Israel but in other countries as well.